[Mistwalker]

Am I missing something here?

Resonance Spike Complex Form: Cracking+Resonance test, each net hit causes 1 point of damage. Fade 4 (likely a bit of fade/stun damage to the technomancer every action)

Matrix Action Data Spike: Cracking+Logic test, AR/2 DV and each net hit causes an additional point of damage. No fade.

Why would a Technomancer ever learn/use Resonance Spike?
Even if their Resonance is at 6 and Logic at 5 (likely set up at Chargen), fade 4 vs no fade, more damage on getting a single net hit....

[CigarSmoker]

Am I missing something here?

yes.
p.190 CRB Resonance Spike
Make a Cracking + Resonance vs. Willpower + Firewall test; each net hit causes 1 box of unresisted Matrix damage.

[Xenon]

Data Spike damage is soaked (like an indirect combat spell)  while Resonance Spike deal unresisted matrix damage (like a direct combat spell).

Ninjad by CigarSmoker

[Finstersang]

Unless your target has a really fat Matrix soak pool, it´s still a pretty shitty deal, though.
The math behind resonance Spike didn´t really hold up back in 5th Edition, so nothing really changed here 

[Xenon]

Actually.... In 5th edition one of them was a Matrix Attack action that would deal unresisted matrix damage back to the hacker in case of a failed attempt or always alert the owner in case of a successful attempt (and in that edition you could also turn off wireless in all your devices at once with a free action). While the other was a Resonance action that for all we know could not be detected at all until smoke started to come out of the device and it simply and mysteriously broke down.

[easl]

Actually.... In 5th edition one of them was a Matrix Attack action that would deal unresisted matrix damage back to the hacker in case of a failed attempt or always alert the owner in case of a successful attempt (and in that edition you could also turn off wireless in all your devices at once with a free action). While the other was a Resonance action that for all we know could not be detected at all until smoke started to come out of the device and it simply and mysteriously broke down.

Except for the hacker taking damage part, I think most of that is still true. Data spike is an illegal matrix action which increases your overwatch score every time you use it. Resonance spike isn't and doesn't.